Question

Show transcribed image textConsider two monochromatic source of light, blue light of wavelength lambda b = 460 nm and red light of wavelength 670 nm. The red light is shun up on a diffraction grating of density, nr = 10,000 lines per cm. A diffraction grating with what line density (lines/cm) is required to have the 2nd maximum (m=2) of blue light coincide with the 1st maximum (m=1) of red light?